Method of color reproduction



Oct. 13, 1964 w. s. MARX, JR 3,152,899

METHOD OF COLOR REPRODUCTION Filed June l0, 1959 FIG, 1

nwvnnmgllun 'mumlllwww l INVENToR. limitar Marx, Jr,

BY uw-vp )Q5/14,7%.

r/zeg United States Patent O 3,152,899 g METHOD OF COLOR REPRODUC'HONWalter S. Marx, ir., Santa Barbara, Calif., assigner to Printing ArtsResearch Laboratories, Inc., Santa Barbara, Caiif., a corporation ofDelaware Filed `tune I6, 1959, Ser. No. 819,395 it) Claims. (Ci. Qdi-30)This invention relates to a method of color reproduction, and moreparticularly to a method of preparing and using art copy for obtainingprinted reproductions thereof in full color without the necessity ofmaking the usual photographic color separations through colored lightfilters.

One of the general objects of this invention is to provide an eliicientand effective method which is much less expensive than those nowcommonly in use for creating and accomplishing the printed reproductionof art copy in color.

My method comprehends the use, in art copy, f a

Vtransparent. color medium adapted to use on colorless transparentfilm-type overlay sheets to produce combinable color-separated overlaysheets which are each suited to reproduction as individual halftoneplates that are combinable for full color printing purposes.

`Another object of my invention is to provide a method of colorreproduction in which screened halftone negatives can bemade onorthochromatic film from pre-separated color parts of art copy, therebyavoiding color separation by light filters and the less readilycontrolled processing of panchromatic film. p It is another object ofthis invention to provide a method of color reproduction of art copy,which method eliminates both the use and the inefficiencies ofcolor-separation lilters, and thereby avoids the later corrective stepswhich are necessary to compensate for the inefficiencies ofcolorseparation filters.

This invention` further has within its purview the provisions of amethod of printed reproduction by a halftone process which utilizes artcopy comprising a composite of transparent separable color layers onsubstantially colorless transparent film overlay sheets and each ofwhich color layers embodies an absorbent of ultraviolet light, so thathalftoneV screen pattern can be eliminated from the uncolored highlightand/or background areas by an additional exposure made with ultravioletlight and with the screen removed.

As another object, my invention comprehends the provision of a method ofreproduction which includes the use of art copy made up of a pluralityof different transparent monochromatic color images on sheets oftransparent hlm-type material that are relatively stable dimensionallyunder various normal conditions of use and are made to register with aline drawing on paper, and each of which color images, as well asthelinedrawing, is individually reproducible for composite reproduction.

In the production of art copy of the type to which reference has beenmade, this method has within its pur- View the use of transparent colormaterials which are desirably quick drying in character to the extentthat they vwill dry to a flexible solid form in a matter of a fewyminutes to conserve the artists time and which can be quickly androughly blocked over areas larger than those which are finally to becolored by making a few quick brush strokes, and then readily andselectively removed the invention will be i SJS@ Patented Oct. 13, T964ice FIG. 1 is an exemplary illustration of finished art copy depictedsymbolically as being in full color, and affords an illustrative exampleof art copy produced by my preferred method, as disclosed herein;

FIG. 2 is a front elevational View of basic components utilized in theproduction of art copy by my disclosed method and includes a base sheethaving thereona key drawing in black and white and having hingedlysecured thereto a plurality of substantially colorless, transparentfilm-type overlays which are each of a size to cover the key black andwhite drawing.

FIG. 3 is an illustration of the key drawing, as rendered in black andwhite, with intermediate shades of gray;

FIG. 4 is an illustration of one of the transparent overlay sheets, asrendered in a transparent blue coloring material, while utilizing thekey drawing as a guide for the placement of the color;

FIG. 5 is an illustration of another of the transparent hlm-type overlaysheets, as rendered in red, while utilizing the key drawing to indicatethe area to which color is applied;

` or strokes in a manner such that it overlays the area A panyingdrawings in which similar characters of reference indicate similar partsthroughout the several views.

which is nally to be covered, in accordance with a preferred manner ofutilizing a portion of my method, as disclosed herein; and

FIG. 8 is a view similar to FIG. 7, but indicating the red coloringmaterial after portions of that applied as f illustrated in FIG. 7 havebeen removed to bring the coloring material into register with theportion of the key drawing which is to be reproduced in red.

The accompanying drawings depict exemplary components and steps, forillustrative purposes, which are adapted to use in preparing art copyand making halftone reproductions therefrom in full color, without theaid of color-separation filters as in isolating primary colors for theusual methods of color printing. While the exemplary illustrationsassume that the final reproductions are to be made to embody the colorsof three primary hues and combinationsV thereof, in addition to a blackand white.

rendering for outline purposes and for changing the values of the huesalong the gray scale by the variation of the gray content of the colorhues, it may be readily understood that many illustrations forcommercial or other purposes may require only one or two of the c olorhues for full reproduction of the coloring of the original art copy. Inthe latter instance, the unneeded primary color hue or hues, or thereproduction of the black and white key drawing may be eliminated.

Having reference to the drawings for the consideration of the materialsutilized, FIG. 2 depicts a preferred basic arrangement of parts for thepreparation of art copy, wherein a black and white key or base drawingiti is made, in a desired size, on a sheet 12 of white opaque material,such as one of the usual and commonly used types of artists board. Inthe-disclosed key or base drawing 10, the exemplary pictorialrepresentation includes a house 13 having a Window 14, a door 15, afront f Wall lr6-in which the window i4 and door 15 are located, an endwall 17 and a roof 1?. Within the picture format, the house issurrounded by a sky area i9 and a foreground area 2) which are dividedby a horizon line 22. Outside of the format of the base or key drawingl0, the artists board is desirably provided with side marginal portions2.3 and 24 and top and bottom marginal portions 25 and l ze.

As depicted in -FlG.j3, the limits of the format, the outline of thehouse E3 including the Window 14 and door l5, and the horizon line 22are drawn in black lines. To add depth, contours and realismnto the baseor key drawing, the end wall 17 of the house and the window 14 and doorare shaded by washes in appropriate shades of gray. Also, a shadow area27 in the foreground adjacent the end wall 17 of the house, end portions28 and 29 of the roof and a portion 3% of the front wall adjacent thelower edge of the roof are also shaded by gray Washes.

For adding color to the base or key drawing for reproduction purposes bymy disclosed method which avoids the necessity of later colorseparations through color separation filters for producing halftoneplates, l .hingedly secure to the marginal portions of the artistsboard, at positions spaced from the format of the key or base drawing10, overlay sheets 32, 33 and 3d of substantially colorless andtransparent film-type material which are each of a size individually tooverlay the full format of the base or key drawing. The termssubstantially colorless and colorless, as used herein, refer to the factor provision that the overlay sheets have no hue or color in themselveswhich will change or polute the colors applied thereto and the making ofcolor separated reproductions therefrom for the purposes oit the processand that would be visually discernible in the final reproduction.Although the film-type overlay sheets 32, 33 and 34 may Vbe secured inplace by various means, such as staples or thumb tacks, the illustrativedisclosure of FIG. 2 shows the sheets hingedly secured to separatemarginal portions Z3, 21d and 25 of the artists board by strips 35, 36and 37 of an adhesive material, such as pressure-adhesive tape l whichholds the sheets rmly and accurately in position, as Well as providing ahinge for swingingthe individual sheets to positions over or awayfrom'the base or key drawing. lt may be observed that by having theindividual transparent sheets 32, 33 and 34 secured to the artists boardat positions spaced from separate sides of the base or key drawing, thesheets can be individually manipulated relative to the drawing andrelative to one another without interference.

As one very satisfactory material adapted to use for the substantiallycolorless, transparent film-type material of the overlay sheets 32, 33and 34, I have used the clear polyester sheets, such, for example, asthe sheet material commonly known commercially as Mylar produced by E.I. du Pont de Nemours & Co. (inc.) of Wilmington 98, Delaware. Thismaterial, in addition to being substantially colorless, clearandtransparent, is impervious to most solvents, so'that coloringmaterial cannot pass therethrough to the Vbase or key drawing. Mylar isalso durable, flexible and very stable in various conditions 0ftemperature and moisture.V It also provides a surface to which atransparent coloring material of a desirable type will adhere and fromwhich it can be removed readily without damage to the transparentfilm-type sheet.

As has been indicated, the three overlay sheets of transparent film-typematerial are provided for making full color renditions for reproductionwith the three primary hues, blue (Cyan), red (Magenta) and yellow eachapplied to individual sheets of the transparent vfilm-type ma' terial,so that each hue is individually applied in preparing the art copy andis individually used in making the line and/or halftone plates forreproduction purposes. By utilizing transparent coloring materials, thecolors are mixed for visual observation when they overlay one anotherand can be viewed inptheir combined aspect in the original art copy, aswell as when reproduced by printing. Y

Although the particular composition and ingredients of the transparentcoloring material used in the method disclosed in this application arenot being claimed specificallyV as a part of this invention, va briefand exemplary kdisclosure directed to that phase of the materials usedor usable in carrying out the steps of my method is presented herein forclarity and completeness in the understanding of the method. It may beobserved that the coloring material has been made to embody certainunusual characteristics which are particularly suited to the methodherein disclosed and which are utilized in the practice of the method.

In addition to being transparent, so that preselected hues mix orcombine visually when applied separately to individual sheets oftransparent film-type material and viewed in superimposed relationshipagainst a white background, the coloring materials used in this methodembody an absorbent of ultraviolet light in the wavelength range between340 and 410 millimicrons, are desirably quick drying to a relativelyhard and flexible condition to facilitate use, and are yreadilysoftenable by the application thereto 0f a liquid which is not a solventofthe coloring materials; the coloring materials, when thus softened,being easily removable to sharply defined limits without dilution ordeterioration of the color adjacent the position of removal.

Considered generally, and for exemplary purposes, a coloring materialcomposition adapted to uses in carrying out the herein discolsed methodmay consist of:

(i) A resin, or combination of resins to serve as a binder or filmIformer.

(2) A solvent, or blend of solvents, for the selected resin, to providefluidity to the coloring material.

(3) A hydrophilic agent, or combination of such agents (for attracting aliquid other than a solvent of the coloring material, after it has driedand hardened, t0 soften the coloring material and lthereby permitease-of removal thereof) which, in this illustrative example, attractswater into the dried and hardened lm of coloring material to effect theease of removal, as by scribing in a manner and with an instrument whichis harmless to the surface to which the coloring material is applied.The hydrophilic agent may also serve as a plasticizer or softener forthe hlm of colorlng'material, or vother plasticizers may be added. v

(4) An absorbent, or group of absorbents, of ultraviolet lightwithin thewavelength range of 340 to 410 millimicrons. y Y

(5) A dye, or dyes, to provide the desired hue in the coloring material.

As a more yspeciiic example of a coloring material suited to use in mydisclosed ymethod Yand embodying ingredients of the types outlined is asfollows.

Solvent blend:

Blend- By volume 2-ethoxyethanol (Cellosolve) percent 25l-methoXy-Z-propanol -do l5 Isopropanol (99%) do 60 Solids:

(PlasticizeU-coconut oil gram-- 0.05 (Hydrophilic agent)-Triton GRS ml--2.0i) (ResirU-ethyl cellulose, 7 cps grams-- 2.80 (Ultravioletabsorbers)- rfi-methyl, 7 diethyl amino coumarin gram- 0.30 2,2,4,4tetrahydroxy benzophenone grams-- 2.30 (Dyes)- Victoria Blue B (Du Pont)gram 0.40 Methyl Violet 2B (National v Aniline) do 0.09

The foregoing-exemplary formulation provides a good'` combination ofcommercial dyestulfs to produce a tri-- stimulus blue" Asatisfactory'red coloring material is.

made in the same formulation by using (instead of the blue dyes) 0.47gram of Azosol Fast Red BE (General Aniline and Film Corporation) and.1l gram of para rosaniline acetate. A satisfactory tri-stimulus yellowis made, in like manner, by using 1.0 gram of Azosol Fast Yellow GRA(General Aniline and Film Corporation).

Referring again to the drawings, FIG. 4 represents the blue (Cyan)overlay, as produced by the artistA on the ,transparent film-type `sheet32, while that film-type sheet 'is placed over the key or base drawingl0. The portions -of the base drawing covered by shades of blue on thefilm-type sheet 32 include the sky area 19, the foreground 20, portionsof the Window 14 and door 1S and portions of the shaded areas of the endwall 17 and roof 18.

FIG. 5 depicts the red (Magenta) overlay, as produced on the transparentfilm-type sheet 33, while that sheet overlays the key or base drawing10. In this instance, the red (Magenta) hue is applied to the exteriorof the roof 18 of the house. lt may be observed that by applying the red(Magenta) coloring material over the full area of the roo-f, that huewill overlay the blue in the shaded end portion of the roof when theoverlays on the `film-type sheets 32 and 33 overlay one another inregister with the base of key drawing. This will, of course, produce acombination or purple hue, and the latter hue will be darkened along thegray scale atrthe portion 28 of the roof which is shaded by a gray washon the base or key drawing. FIG. 6 illustrates the yellow overlayasproduced by the application of yellow coloring material to the lm-typesheet 34. On this overlay, while the hlm-type sheet 34 overlays the baseor key drawing, various intensities of yellow coloring material areapplied to the foreground` area 2h, the front wall 16, including thedoor and window areas and the end wall l?. When the hlm-type sheets 32and ,34 overlap one another in contact with the base or key drawing, litmay be understood that the foreground areawill appear as green, sincethe blue on the sheet 32 will visually combine with the yellow on thesheet 34. The front wall 16 will appear as yellow and the end wall 17wil have areas of green and yellow, both of which are grayed by the washapplied to that wall on the base or key drawing. When the threetransparent film-type sheets are placed one over the other in -registerwith the ybase or key drawing, the composite result will appear in itsfull range of hues and values as indicated in FlG. 1. Furthermore, whenreproduced in the manner and by the method herein disclosed, thereproduction of the original art copy will appear in its full range ofhues and values, also as shown in FIG. 1.

As has been indicated herein, my preferred coloring materials which areadapted for use in this disclosed method are transparent and are alsosoftenable for easeot removal by the application thereto of a liquidother than a solvent of the coloring material. Being readily remov ablein selected areas or portions without causing dilution or damage to theunremoved coloring material after it has once dried, it has been foundexpedient, in the application of the coloring material, to quickly brushonto an area which is to be covered,"a desired primary hue, withoutparticular regard to the limits of the area to be covered, and to coverall of that area-with some overlap into the surrounding or adjacent areaof the film-,type sheet to which the coloring material is applied.. Thecolor thus applied will llow toa smooth even coating over the area andwill dry to a lirm, durable and hard, althoughlflexible, applied layer,as depicted at 38 in FIG. 7. After being thus applied and dried, thecoloring material which overlaps the desired portion which is to becolored can be readilyremoved, with coloring material of the typedisclosed herein, by moistening any convenient portion of the entirearea with water to soften the dried layed without dissolving or dilutingthe coloring material.

The softened coloring material can then be removedto bring the colorinto exact registry withthe desired portion of the base or key drawingby scribing or frictionally removing the marginal portions with the aidof a tool, such as an orangewood stick, a pencil or a cotton swabwithout in any way imparting damage tothe transparent film-type sheetwhich carries the coloring material. In this manner, the coloringmaterial is brought into registry with the base or key drawing, as shownin FIG. 8.

With transparent coloring materials of the desired hues selectivelyapplied to predetermined areas of the transparent lm-type sheets, withseparate primary hues on each of the nlm-type sheets required forproducing art copy having a desired range of hues, the art copy is readyfor the further steps of my method which are required for the productionof line and/or halftone printing plates suitable for reproductionpurposes. Having the primary hues already separated from the base or keydrawing and from one another, each may be reproduced photo-mechanicallywithout the necessity of the use of colorseparation lters for separatingthe several hues. Furthermore, by avoiding the necessity of the use ofthe color separating light filters in the reproduction process, thehandwerk which is ordinarily required on the printing plates tocompensate for the inemciencies of the colorseparation filters iscompletely avoided.

Individual line and/ or halftone negatives, and evenvtually individualprinting plates are made from each of the individual film-type sheetshaving the separated hues thereon and from the base or key drawing. Thebase or key drawing may be reproduced in either line or halftone, Iasrequired by the original art copy. In either event, the original or keydrawing may be reproduced by-photographing it on orthochromatic filmwhich is practically insensitive to red. It" a line reproduction is tobe made, the base or key drawing is photographed directly, without usinga haltone screen, while if a halftone negative is required, ahalftonescreen is utilized.

Since orthochromatic film is practically insensitive to red, thefilm-type overlay sheet carrying the red coloring material can bereproduced by making a halftone negative of that individual sheetphotographically with the sheet placed against a white background. Thiscan be accomplished byA photographing the film-type sheet carrying thered coloring material through a halftone screen without the aid of alight filter. Similarly, halftone negatives can be made onorthochromatic film from the ilm-type sheets carrymg the blue and yellowcoloring material, but in these instances, contrast lters are desirableto record the `to which reference has been made are obtainable fromEastman Kodak Company of Rochester, .New York.

One of the advantages in the use of orthochromatic film is that it canbe developed with the aid of visual inspection under a red safelight toobtain optimum reproduction` 1 fidelity, instead of being developedwithout inspection by a time and temperature method, as requiredforpanchromatic lm which must be used when color separation negativesare made throughcolor separation iilters. A further aid in optimumreproduction delity in the developing'process when orthochromatic filmis used (so that Visual inspection is possible) is the use `of a grayscale or step-wedge having gray shades in steps from white to black` andhaving a coating of a suitable ultraviolet lightv absorbing materialthereon placed along one Side of the art copywhen it is photographed,and which will serve development during the processing by visualinspection.

This aiiords a means for balancing the exposures and,

processing of the negatives of a set. By affording a comparison of grayshades, it eliminates many problems arisl ing from differences of colorandbrings the negatives into proper and balanced relationships with oneanother when the halftone exposures are madein the manner described.

lt has been pointed out that each of the hues of coloring material usedin the practice of my disclosed method in its preferred `aspectsembodies an absorber of ultraviolet light. This ultraviolet lightabsorbing characteristic which is imparted to the coloring material bythe inclusion of the absorber therein is utilized to eiiect theproduction of clear (dotless) highlight areas, while leaving the fullhalftone reproduction in colored and shaded areas. To etlect this resulta supplementary exposure Vis made by ultraviolet light and with thehalftone screen removed, and in register with each halftone exposure.This is accomplished by using light sources, such as standard carbon arclamps or mercury vapor arc lamps, which radiate amply across both thevisible and ultraviolet spectrum, thereby to provide yan adequatequantity of ultraviolet, blue and yellow light to permit the use ofcomplementary filters for making the exposures for the blue and yellownegatives, in addition to furnishing the ultraviolet light for theexposure by which screen pattern is removed from the highlight areas.

-t During the supplementary exposure by which dot pattern is removedfrom the highlight areas, the hali'tone screen is not only removed fromthe camera, but a iilter is used at the camera which passes ultravioletlight while absorbing visible light.V It may be readily understood thatsince the coloring materials used absorb ultraviolet light, andparticularly since the light passes through such coloring material twicein travelling from the source to the reiiective background and back tothe camera, the correi sponding areas on the negative are unaiected bythe ultra-V violet exposure, while ultraviolet light is freely refiectedfrom the white backing sheet through uncolored areas of the art copy, toeliminate halftone pattern from corre` spending areas of the negativewhen the ultraviolet exposure is made with the halftone screen removed.V

It is considered worthy of note that my herein disclosed method affordsthe ample ability and efciency for recording and holding open halftonedots or pattern in the areas of the negative corresponding to the verylight values on the blue and yellow overlays, while providingl for therecording ofY ample negative density in highlighted areas on the samenegative. Y y

In some'instances, it may be found desirable to use two transparentfilm-type sheets for carrying parts or added amounts of the same primaryhue. In this instance, those two transparent iilm-typesheets arephotographed together to make a single composite halftone negative andcolor plateL The two transparent film-type sheets must, of course, be inregister when photographed and the general procedure of makingthehalftone negative from the two sheets is the same as that used when thef color is on a single sheet, utilizing both an exposure through ahalftone screen and an unscreened exposure with ultraviolet light. v

From the foregoing description and reference to the accompanyingdrawings, it may be readily understood that I have provided a method ofcolor reproduction which has many advantages to both the artist in thepreparation of the art copy and the photoengraver or lithographer in thepreparation and processing of letterpress or ,lithographic printingplates used for reproduction of the ait copy. Thercoloring materials arequick drying andcan f berapidly used. They can be kept strictly inregister with a base or key drawing by the application of color todesiredl areas and then scribing the color to lines oi reggister withthe aidof a liquid softener whichdoes not dilute or deteriorate theVVapplied color. Also, color canV be i readily removed from eithermarginal or particularly deined areas without any damage to either thekey drawing or the sheet to which the color is applied. Art copyproduced by the disclosed method is subject to reproduction onorthochromatic Viilm with the aid of visual inspection during processingand with a considerable saving of both time. and expense, as well aswithout the necessity of producing color separation negatives throughlight iilters on panchromatic Llm. Color corrective masking and theneedfor skilled handwork on the halftone plates are both eliminated bythe inherent preseparation of the color aorded by this method and by theincorporation of an ultraviolet light absorbent in the coloring materialwhich makes possible the use of a supplementary unscreened exposure foreliminating the dot pattern from highlight and background areas.Furthermore, the plates produced by this method result in the productionof rinted copy which is clear, sharp and crisp, with a live brillianceand color purity which is seldom achieved in the reproductions made withcolor separation ilters.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A method of multi-color reproduction and wherein a plurality of huesare separated in art copy as prepared, said method comprising the stepsof making a monochromatic guide drawing on al base surface whichreflects ultraviolet light, covering the guide drawing with an overlaysheet of substantially colorless and transparent filmtype material whichtransmit ultraviolet light, applying Vtransparent liquid coloringmaterial containing an abcally producing separate and individualnegatives directly from said base art copy and said voverlay sheet onorthochromatic film, the photographic production of a negative from saidoverlay sheet being characterized by the steps of making onephotographic exposure of the overlay sheet against a white backing whichis reflective of ultraviolet light and through a halftone screen withlight principally made up ofwavelengths other than ultraviolet, andmaking a second photographic exposure Without the halftone screen andwith light limited substantially to the ultraviolet wavelength range toprovide clear delineation between color and noncolor areas and Vtoeffect removal of halftone dots from the non-color areas.

2. A methodof multi-color reproduction as defined in claim 1, andwherein said transparent liquid coloring material is initially appliedto an area overlapping said portion of the guide drawing with which itis to register, and then parts of the coloring material are removed toeliect said register.

3. A method of multi-color reproduction as defined in claim 1, andwherein the `transparent liquid coloring material applied to saidoverlay sheet has a hue other than black or red, said fone exposurewhich is made through la halftone screenis also'made through a lightlter having a color which is substantially the complement of the huebeing photographed, and the negatives g produced by said exposures aredeveloped'to the desired density by visual inspection of of the lmduring development with the aid of non-actinic light.

4. yAmethod of multi-color reproduciton as detined in claim` 1, andwherein said hue of the transparent liquid coloring material applied tothe overlay sheet is red, said one photographic exposure'which is madethrough a halftone screen is made on orthochromatic filmwithout a lightfilter, and-then after the second photographic exposure thel developmentof vthe orthochromatic film is accomplished with the aid of visualinspection during development in non-actinic light. f v

l5. A method of `multi-color reproduction wherein a plurality of primarycolor huesare' separated inl the material of each of the primary colorhues used to a separate sheet of substantially colorless transparentmaterial, said method comprising the steps of applying transparentcoloring material of each primary hue used and containing an absorbentof ultraviolet light to a selected portion of a separate and individualsheet of substantially colorless transparent material which transmitsultraviolet light, mounting each sheet of substantially colorlesstransparent material having the transparent coloring material thereonagainst a sheet of white backing material which reiiects ultravioletlight, making two photographic ex.- posures of each mounted sheet onorthochromatic film while using a light source which emits light in boththe visible and ultraviolet spectrum ranges, one of said two exposuresbeing made by light in both the visible and ultraviolet ranges andthroughl a halitone screen, and the other of said exposures being madeWith the halftone screen removed and with the light substantiallyrestricted to the ultraviolet range, said other of the exposures beingmade to increase the negative intensity of areas of the iilm notincluded in the image of the colored portion of the transparent sheet,thereby toprovide delineation of even lightl ly colored parts of thecolored portion and eiect removal of the halftone screen pattern fromthe photographic image of the uncolored area, and eliecting balancebetween the densities of negatives produced by said exposures `by visualinspection during development with the aid of non-actinic light.

eifect the reduction of the areaV thereof to said selected n Y typematerial which transmits ultraviolet light, manually creating an imageof transparent coloring material containing an absorbent of ultravioletlight and of a hue different than that of the guide drawing on saidoverlay sheet, which image is in register with a portion of the guidedrawing, separating said overlay sheet from the base art copy, andphotographically producing separate and individual negatives directlyfrom said base art copy and said overlay sheet, the photographicproduction of a negative from said overlay sheet being characterized bythe steps of making one photographic exposure of the overlay sheet onorthochromatic ilm against a backing which is reiiective of ultravioletlight and through a halftone screen with light principally made up ofwavelengths other than ultraviolet, and making a second photographicexposure in register with the said one photographic exposure on the sameiilm without the halftone screen and with light limited substantially tothe ultraviolet wavelength range to provide clear delineation betweenindividual color areas and non-color areas and to eiiect removal of halftone dots from the non-color areas, and controlling the density of thenegatives produced by the visual inspection thereof in non-actinic lightduring development.

8. A method of multi-color reproduction as dened in claim 7, and whereinsaid image of transparent coloring material initially overlaps saidportion of the guide drawing with which it is to rigister, and thenparts of the coloring material are softened and then removed to eiiectsaid register.

9. A method of multi-color reproduction as defined in claim 7, andwherein the transparent coloring material of said image on said overlaysheet has a hue other than black or red, said one exposure which is madethrough a halitone screen is also made through a light iilter having acolor which is substantially the complement of the hue beingphotographed, and said one eX- posure has a duration which compensatesfor the presence of said light ilter.

10. A method of multi-color reproduction wherein a plurality of primarycolor hues are separated in the preparation of art copy by the use onindividual separate sheets of substantially colorless transparentmaterial of coloring material of each of the primary color hues, saidmethod comprising the steps of preparing individual sheets ofsubstantially colorless transparent material which transmits ultravioletlight by manually deiining on each sheet a selected area of one of theprimary hues used and which contains an absorbent of ultraviolet light,mounting each sheet of substantially colorless transparent materialhaving the transparent coloring material thereon against a sheet ofbacking material which reflects ultraviolet light, making twophotographic exposures of each mounted sheet on orthochrornatic lm Whileusing a light source which emits light in both the visible andultraviolet spectrum ranges, one of said two exposures being made bylight in both the visible and ultraviolet ranges and through a halftonescreen, and the other of said exposures being made with the halftonescreen removed and with the light substantially restricted to theultraviolet range, said other of the exposures being made to increasethe negative density of areas of the iilm not included in the image ofthe colored portion of the .transparent sheet, thereby to providedelineation of even lightly colored parts of the colored portion andeiect removal of the halftone screen pattern from the photographic imageof the uncolored area, and iinally balancing the negative densitiesresulting from the exposures of the separated color hues by visualinspection during development in non-actinic light.

References Cited in the file of this patent UNITED STATES PATENTS2,071,136 Mzeinzinger Feb. 16, 1937 2,273,567 Fishel Feb. 17, 19422,304,942 Marx Dec. 15, 1942 2,336,590 Bourges Dec. 14, 1943 2,353,867Balcomb July 18, 1949 2,628,903 Kott Feb. 17, 1953 2,907,657 Kott Oct.6,V 1959 3,025,627 Misturini Mar. 20, 1962 FOREIGN PATENTS 51,116Germany Feb. 15, 1890 17,638 Great Britain of 1905 OTHER REFERENCES TheLithographers Manual, vol. 1, pages 4:82-83 and the 4 page insertbetween, Waltwin Pub. Co., 317 W. 45th St., N Y. 36, NY., January 1958.

The Fluorographic Drop-Out Method for Half-Tone Highlight, ThePhotoengravers Bulletin, March 1959, pp. 39-42.

1. A METHOD OF MULTI-COLOR REPRODUCTION AND WHEREIN A PLURALITY OF HUESARE SEPARATED IN ART COPY AS PREPARED, SAID METHOD COMPRISING THE STEPSOF MAKING A MONOCHROMATIC GUIDE DRAWING ON A BASE SURFACE WHICH REFLECTSULTRAVIOLET LIGHT, COVERING THE GUIDE GDRAWING WITH AN OVERLAY SHEET OFSUBSTANTIALLY COLORLESS AND TRANSPARENT FILMTYPE MATERIAL WHICH TRANSMITULTRAVIOLET LIGHT, APPLYING TRANSPARENT LIQUID COLORING MATERIALCONTAINING AN ABSORBENT OF ULTRAVIOLET LIGHT AND OF A HUE DIFFERENT THANTHAT OF THE GUIDE DRAWING TO SAID OVERLYA SHEET IN REGISTER WITH APORTION F THE GUIDE DRAWING, SEPARATING SAID OVERLY SHEET FROM THE BASEART COPY, AND PHOTOGRAPHICALLY PRODUCING SEPARATE ANDINDIVIDUALNEGATIVES DIRECTLY FROM SAID BASE ART COPY AND SAID OVERLAYSHEET ON ORTHOCHROMATIC FILM, THE PHOTOGRAPHIC PRODUCTION OF A NEGATIVEFROM SAID OVERLAY SHEET BEING CHARACTERIZED BY THE STEPS OF MAKING ONEPHOTOGRAPHIC EXPOSURE OF THE OVERLAY SHEET AGAINST A WHITE BACKING WHICHIS REFLECTIVE OF ULTRAVIOLET LIGHT AND THROUGH A HALFTONE SCREEN WITHLIGHT PRINCIPALLY MADE UP OF WAVELENGTHS OTHER THAN ULTRAVIOLET, ANDMAKING A SECOND PHOTOGRAPHIC EXPOSURE WITHOUT THE HALFTONE SCREEN ANDWITH LIGHT LIMITED SUBSTANTIALLY TO THE ULTRAVIOLET WAVELENGTH RANGE TOPROVIDE CLEAR DELINEATION BETWEEN COLOR AND NONCOLOR AREAS AND TO EFFECTREMOVAL OF HALFTONE DOTS FROM THE NON-COLOR AREAS.